How The Cutting Skill Ten-Uchi Affected Japanese Bladesmithing

Japan's feudal period is regarded as being the pinnacle of bladesmithing. While this period was largely defined by warring rulers and their armies, it was an important time for the region because it had developed new, more effective ways to create swords. Around the Kamakura Period, for example, Japanese bladesmiths began using high-carbon steel (tamahagane) as well as differential heat treatment to create single-edged, curved swords that were superior in nearly every way to their predecessors.

Japanese samurai warriors used these high-quality swords primarily as weapons in their battles. Whether these battles were performed in the field, mountains, coast or elsewhere, samurai warriors would often carry at least two swords to attack and defend themselves against their opponents. To prepare for such battles, though, samurai warriors would perform special cuts, known as ten-uchi, on practice targets. So, what is the ten-uchi cut exactly, and why was an important skill for samurai warriors?

Overview of Ten-Uchi

Ten-uchi is a special cutting technique that involves making an organized arm and wrist motion so that the sword snaps down upon a test target or opponent. When the samurai warrior swings the sword downwards, it causes his elbow to extend, thereby allowing for a snap-like "pop" when the sword reaches the target. Some sword historians compare the ten-uchi to the motion of flicking a wrapped up wet towel.

With ten-uchi, the general idea is to raise the sword above your body -- while holding it with both hands -- and quickly bring it back so that it hits the target at the precise time that your elbows extend completely. The full extension of your elbows will stop the blade. And this forced stop creates additional strength that can break through armor, making ten-uchi an invaluable skill for samurai warriors in feudal Japan.

Significance of Ten-Uchi

Ten-uchi allowed samurai warriors to develop the skills and proficiency needed to defend themselves against invading forces, including the Mongols. When the Mongols invaded Japan, samurai warriors initially had trouble defending against them because they wore thick leather-boiled armor. Power attacks like the ten-uchi, however, allowed samurai warriors to penetrate their armor and gain the upper hand on their opponents.

In addition to being used in combat, ten-uchi has also been used extensively in the testing of traditional Japanese swords. Tameshigiri, for example, often incorporates ten-uchi or similar cutting styles in its practice.